Exposure to diesel exhaust for an hour during exercise impairs blood vessels’ ability to expand for greater blood flow. Volunteers, who were placed in a closed chamber and asked to exercise on a stationary bike, were subjected to the level of diesel exhaust comparable to what a pedestrian breathes curbside in a large city. After such exposure, the volunteers’ forearm blood flow decreased significantly.

The results of the study may convince you that mall walking or other indoor exercise is the way to go if the outside air is polluted.

The U.S. Environmental Protection agency is sponsoring a voluntary diesel retrofit program to reduce dangerous emissions from construction equipment and heavy-duty trucks on the road.